Toothbrush with elastomer filled flexible head

ABSTRACT

A toothbrush, having a handle ( 12 ) and at one end thereof a bristle-bearing head ( 11 ), wherein the head ( 11 ) is in the form of two or more segments ( 15 ) flexibly and/or resiliently linked to each other and/or to the handle ( 12 ), one or more of the segments ( 15 ) being bristle bearing.

SUMMARY OF THE INVENTION

The present invention relates to a toothbrush, more particularly to atoothbrush with a comprising regions of elastomer in both the head andthe handle wherein one or more elastomer supply channels connect theregions so that they can all be filled with elastomer from a singleinjection point.

BACKGROUND OF THE INVENTION

The configuration of human teeth requires that the ideal bristle contourfor toothbrushes for brushing the buccal or outside surfaces of teeth beconcave and that the ideal bristle contour for brushing the lingual orinside surfaces of teeth be convex. Most brushes have a single piecehead which is of comparable thickness to the handle and which isrelatively rigid and of a fixed curvature or configuration.

A further drawback of conventional brushes is that pressing the brushsufficiently hard against the teeth to get good cleaning risks damagingor discomforting the softer, adjacent gums. To a certain extent this canbe solved by modifying the configuration of the brush, or by varyingbristle hardness or length, though again, a single configuration cannotbe optimum for all circumstances.

Some brushes mat, however, incorporate a means for allowing the head toflex relative to the handle, as described for example in EP-A-371,293.Even so, such brushes have limited effectiveness. Other brushes areknown which are adjustable into several different but fixedconfigurations. Adjustable toothbrushes are often difficult tomanipulate and may be unreliable.

WO 92/17093 discloses a toothbrush having a handle and at one endthereof a bristle-bearing head, wherein the head is in the form of twoor more segments flexibly and resiliently linked tan each other and/orto the handle, one or more of the segments being bristle bearing. In oneembodiment this is achieved by the use of transverse, and optionallylongitudinal, grooves on the opposite face of the head to the bristles.The grooves can be wholly or partially filled with an elastomer.

Co-filed application WO 92/17092 further discloses a toothbrush having ahandle and at one end thereof a bristle-bearing head which is flexiblyand resiliently lid to an extended portion of the handle. The spacebetween the head and the handle may be filled with an elastomer. Theapplicant markets a brush called the ‘Schwingkopf’ under the name ‘Dr.Best’ which contains some of the features disclosed in WO 92/17092. Thebrush has an elastomeric handle grip and an elastomer filled grooveconnecting the grip to an elastomer filled region in the neck of thebrush. However, the brush does not contain transverse grooves in thehead.

It is well-known to provide elastomeric grips in the handles oftoothbrushes. It is also known from the above-mentioned PCT applicationsto provide transverse grooves containing elastomer into a brush head. Tothe present applicant's knowledge however, it has not been disclosed howboth these objects can be achieved using a conventional single-point,injection moulding process.

It has now been found that all of the elastomer filled areas of thebrush can be filled by a single-point injection moulding process byproviding one or more elastome supply channels which connect the groovesin the head to the grips in the handle.

It is accordingly an object of this invention to provide a toothbrushwith a flexible head and handle grips which can be made by a simpleinjection moulding process.

It is yet a further object of this invention to provide a toothbrushwhich has good long-term durability.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided atoothbrush, comprising:

i) an elongated handle having distal and proximal ends and one or moreelastomeric handle regions therein; and

ii) a resiliently flexible head attached to the proximal end of thehandle, the head including a pair of opposing faces, one of the pairbeing a bristle-bearing face with bristles attached to and extendingfrom the face, wherein at least one of the pair has one or moreelastomer-containing, transverse grooves therein; and

iii) one or more elastomer supply channels extending between theelastomeric handle regions and the transverse grooves,

whereby at least one of the elastomeric handle regions and thetransverse grooves can be filled with elastomer from a single injectionpoint.

According to a second aspect of the invention there is provided atoothbrush, comprising:

i) an elongated handle having distal and proximal ends and one or moreelastomeric handle regions therein; and

ii) a resiliently flexible head attached to the proximal end of thehandle, the head including a pair of opposing faces, one of the pairbeing a bristle-bearing face with bristles attached to and extendingfrom the face, wherein each of the pair has one or moreelastomer-containing transverse grooves therein, the grooves dividingthe head into segments which are flexibly connected by hinges, whereineach hinge is located between the opposing faces and at a distance of atleast about 10% of the depth of the head from each of the faces, thehinges being less than the full width of the head; and

iii) one or more (elastomer supply channels extending between theelastomeric handle regions and the transverse grooves,

whereby at least one of the elastomeric handle regions and thetransverse grooves can be filled with elastomer from a single injectionpoint.

The toothbrush of this invention comprises a handle includingelastomeric regions, which can be used to improve the user's grip on thehandle, and a head which has transverse grooves, that allow the head toflex under the action of brushing and accommodate itself to, forexample, the differing profiles of individual users' teeth. The headfurther includes elastomer contained within the grooves on at least oneface. The elastomer improves the resilience of the head by acting like aspring, so that when a force applied to bend the head is removed, thehead returns within a short period of time to its originalconfiguration. The toothbrush further comprises one or more supplychannels which connect the elastomeric regions in the handle to thetransverse groove in the head enabling the elastomer in both the headgrooves and handle regions to be supplied from a single elastomerinjection point. The grooves divide the head into segments and definehinges which connect the segments. Preferably, there are transversegrooves on both of the opposing faces and the hinges are located betweenthe faces so that they are subject to the minimum amount of tension orcompression. In this case the hinges are preferably less than the fullwidth of the head so that elastomer can flow from one face of the had tothe opposing face. The interconnectivity of the elastomer containingparts enables all of them to be filled with elastomer using asingle-point injection moulding process on conventional equipment.

DETAILED DESCRIPTION OF THE INVENTION

Handle

The toothbrush of this invention comprises an elongated handle havingdistal and proximal ends and one or more elastomeric handle regionstherein. The handle can be of shape and external dimension suitable fortoothbrushes. The elastomeric regions in the handle are generallydesigned to act as hand or finger grips but they can be provided forsolely aesthetic purposes, for example to give the brush a distinctiveappearance. The elastomeric regions can be flush with the surface of thehandle or raised or recessed from the handle surface. Preferably atleast a part of one elastomeric region is raised for providing bettergrip. In general the elastomeric regions are provided by initiallymoulding the handle the handle to comprise voids which are then filledby the elastomer in a separate injection moulding step. The voidsprovide some physical entrapment of the elastomer, but preferably theelastomer is chosen so that it becomes bonded to the handle materialthrough the injection moulding process. The voids can be arranged sothat when filled with elastomer the various elastomer regions, at leastwhen handle material is opaque, give the appearance of being completelydiscrete. At least one, preferably all, of the elastomeric regions inthe handle is connected by the elastomer supply channel(s) describedbelow to the transverse grooves in the head. Typically, the elastomer inthe grips of the handle is a substantial part of the total volume ofelastomer to be injected. For this reason the elastomer injection pointis preferably located at the distal end of the handle. In this context,‘at the distal end of the handle’ means that the injection point islocated closer to the distal end than to the proximal end of the handle.

The handle, and also the toothbrush head, are generally made ofrelatively non-compressible materials, preferably with a modulus ofelasticity of at least about 500 MPa, more preferably at least about1000 MPa, which are conventional in the manufacture of toothbrushes,especially plastics materials. Suitable plastics materials include, forexample, polyamides and polypropylenes. Polypropylene is preferred.Suitable polypropylenes include the material ‘Polypropylene PM 1600’(marketed by Shell), having a modulus of elasticity (ISO 178) of 1500MPa and Apryl 3400 MA1 from Elf Atochem. Preferably, a foaming agentsuch as Hydrocerol HP20DP from Boehringer-Mannheim is mixed with thepolypropylene at a level of from about 1% to about 3%, preferably fromabout 1.5% to about 2.5%, by weight of the polypropylene. The foamingagent assists the flow of the polypropylene during moulding and, inparticular, helps to ensure uniform formation of the hinges in the head.

Suitable elastomers for use herein include thermoplastic elastomers witha Shore hardness of 30-80 and a modulus of elasticity of less than about500 MPa, preferably less than about 300 MPa, such as SANTORPRENE andTHERMOFLEX. An exemplary elastomer is ‘PTS THERMOFLEX 75’ (marketed byPlastic Technologie Service, Germany), having a Modulus of elasticity(ISO 178) of 100 MPa and a hardness (ISO 868) of 80 Shore A. ElastomersPL12291, PL12292, and PL12293 (marketed by Multibase, Saint Laurent DuPont, France) are also suitable for use herein. In general, choosing theelastomer so that is based upon the same chemical class of polymers asmaterial of the head segments assists in bonding the elastomer to thehead segments. For example, when the head segments are made frompolypropylene, the elastomer is preferably based upon polypropylene. Theelastomers can optionally be mixed with a suitable plasticiser orfoaming agent to make them more compressible. The colour of the(elastomer material can be the same as that of the head segments, or itmay be different thereby achieving a distinctive striped or otherwisepatterned appearance.

The handle itself is generally rigid. Optionally, the handle maycomprise a neck portion which is more flexible than the rest of thehandle, as known in the art, provided that it is sufficiently rigidthat, in use, when force is applied to the head, particularly whenbrushing the teeth, the head still flexes in the manner and to theextent described below.

Head

The toothbrush of this invention further comprises a resilientlyflexible head attached to the proximal end of the handle, the headincluding a pair of opposing faces, one of the pair being abristle-bearing face with bristles attached to and extending from theface, wherein at least one of the pair has one or moreelastomer-containing, transverse grooves therein.

Suitable materials for the head are the same as those for the handle.Preferably the head and handle are co-moulded in a single injectionmoulding step, so that the head and handle form one continuous piece. Inany case the long axis of the handle defines a longitudinal axis of thehead. The head also has a transverse axis lying orthogonal to thelongitudinal axis and generally parallel to the opposed faces.References to transverse or longitudinal herein refer to directionswhich are respectively parallel to these transverse and longitudinalaxes, unless indicated otherwise. The head itself is also generallyelongated, with its elongated axis also being a longitudinal axis.

The head includes transverse grooves on at least one of thebristle-bearing face and the opposing face, the grooves dividing thehead into segments. The grooves allow the head to flex or bend along itslongitudinal axis. This allows the brush head to flex so that itacquires a convex profile along the longitudinal axis when pressedagainst the teeth. This makes it particularly suitable for brushing thelingual or inside surfaces of the teeth. The grooves can be linear ornon-linear, such as curved or zigzag. Non-linear grooves help to offsetcompression stress in the elastomeric material filling the grooves asthe head bends. The term ‘transverse grooves’ as used herein can alsoencompass grooves whose main axis, as defined by the straight linejoining the start and endpoints of the grooves is offset from thetransverse axis of the head by an angle of up to and including 45°. Inpreferred embodiments both the bristle-bearing face and the opposingface include one or more transverse grooves therein.

The head also includes one or more longitudinal grooves on at least oneof the bristle-bearing face and the opposing face. The term‘longitudinal grooves’ as used herein can also encompass grooves whosemain axis, as defined by the straight line joining the start andendpoints of the grooves is offset from the ‘longitudinal axis of thehead by an angle of up to 45°. Longitudinal grooves can allow, forexample, the outer longitudinal rows of bristles to flex away from theinner ones. They also act as elastomer supply channel(s) to thetransverse grooves as described below.

Where there are grooves on both of the opposing faces, grooves on oneface can be directly opposed to grooves on the other face or partiallyor wholly offset. Preferably, the grooves are directly opposed or onlypartially offset.

The grooves, which separate the segments of the head, also definehinges, which are thinned regions of the head at the base of thegrooves.

The grooves can be of variable width and depth and the distances betweengrooves can also be varied. In this manner the flexibility of the headalong the length and/or across the breadth of the head can be modified.Preferably only transverse grooves are varied in this way. Changing thedepth of the grooves controls the location and thickness of the hingeswhich connect the segments. For a toothbrush head of between about 4 toabout 6 mm thickness, typically about 5 mm, suitable groove depths arein the range from about 1.4 to about 3 mm, preferably from about 1.5 toabout 2.8 mm. Suitable hinge thicknesses are in the range from about 0.4to about 2.0 mm, preferably from about 0.5 to about 1.5 mm. Wheretransverse grooves are used then, desirably, the hinges which are orwill be nearer to the handle are less flexible than those which are orwill be more remote from it. In this way more uniform bending of thehead can be achieved. The variation in flexibility can be achieved byvarying the hinge thicknesses. In a preferred embodiment the hingenearest the handle is up to about 3 times, preferably up to about 2times as thick as the hinge most remote from the handle. An exemplaryset of hinge thicknesses for a toothbrush with 3 transverse grooves arerespectively about 1.2, 0.6 and 0.6 mm reading from the handle end. Ifidentical hinges are used along the brush head then there is a tendencyfor flexing of the head to occur predominantly at the hinge nearest thehandle. The depth of grooves on the bristle bearing face can bedifferent to those on the opposing face. Preferably the grooves on thebristle-bearing face are less deep than those on the opposing face. Inembodiments where there is elastomer in the grooves on both faces, thisallows more elastomer to be put under compression than under tension.The elastomer to segment bonds are stronger under compression than undertension.

Increasing the width of the grooves increase the gap between thesegments and therefore the length of the hinges, which increases theirflexibility. However, since it is preferred to insert bristles into thesegments rather than into the elastomer, increased groove length alsoleaves less space for the bristles, within a given head size. Suitablegroove widths are in the range from about 0.3 to about 3.0 mm,preferably from about 1.2 to about 2.0 mm. The grooves are preferablytapered slightly inwards towards the bottom of the groove, suitablyconverging at an angle of from about 3 to about 10°, to facilitatemoulding. As the brush is flexed the width of the groove changes, morerapidly at the top of the groove than at the bottom of the groove, therelative change being a function of the groove width and depth. Sincethis change in groove width results in compression or tension ofelastomer contained within the groove, it can be seen that, for a givenelastomer, the groove geometry can be used to control the flex angle.

The hinges can be the full length of the grooves or, preferably, therecan be one or more gaps in or to the side of the hinges the grooves inthese regions being the full depth of the head. The gap allows elastomerto flow from one face to the other during the moulding process so thatelastomer can be used on both sides of the head and yet still suppliedfrom a single injection point. In a preferred embodiment, the hinges arediscontinuous, with two or more hinges, preferably just two, connectingeach segment to its neighbour or to the handle. In this embodiment thereare gaps between the hinges and to each side. In linear grooves, thehinge widths are not generally critical, provided that they are suchthat gaps are still created, however, wide hinges can be subject todistortion if they are used within a non-linear groove. Suitable hingewidths are in the range from about 0.5 to about 4.0 mm, preferably fromabout 1.0 to about 3.0 mm.

It is preferred that each hinge is located between the two faces and ata distance of at least about 10%, preferably at least about 20%, morepreferably at least about 30% of the depth of the head from each of thefaces. The distance of the hinge from the face is measured by theperpendicular line drawn from the top of the face to the nearestboundary surface of the centre of the hinge. Locating the hinges awayfrom the faces of the brush means that they are subject to lessstretching or compression as the head is flexed and improves theirdurability. In a particularly preferred embodiment, the brush head hastransverse grooves which are arranged in pairs such that one member ofeach pair is on each face and directly opposes the other member of thepair, with one or more hinges therebetween connecting the segments sothat each hinge is located between the two faces and at a distance of atleast about 10%, preferably at least about 20%, more preferably at leastabout 30% of the depth of the head from each of the faces.

The grooves on at least one face of the brush contain elastomer,preferably bonded to the segments of the head. The term ‘elastomer’herein refers to a material which is both elastically compressible andelastically extensible. Thus when the head is flexed in a directionorthogonal to the opposed faces, the elastomer is put either undertension or under compression. The elastomer has the effect of limitingthe head flexibility thereby reducing the stretching or compression ofthe hinges and of limiting the stress at the bond between the elastomerand the head segments. A more durable head is thus obtained. Preferably,grooves on both the bristle-bearing face and the opposing face containelastomer so that elastomer is put under compression whichever directionis chosen. The elastomer on the opposed face is of course put undertension but the tensile stress on the elastomer to segment bonds islimited and is shared with the hinge material.

Preferably all of the grooves are wholly filled with the elastomer.Complete filling of the grooves has an advantage of, for example,avoiding contamination of the grooves by toothpaste deposits. Thegrooves can be partially filled though, provided that sufficientelastomer is used to give effective moderation of the flexibility of thehead.

The whole head has a conventional, generally flattened shape but remainsflexible when compared to that of a conventional brush. By ‘flexible’ ismeant herein that when a 3 Newton force is applied to one end of thehead, the other end being held fixed, the end to which the force isapplied will deflect through an angle of at least 2°. The end of thehead which is to be held fixed is defined by the line which isperpendicular to the axis along which bending takes place and whichtouches the first row of bristles. In the preferred embodiments havingtransverse grooves, where the head bends along the longitudinal axis,the end should be that which connects to the handle. The end of the headwhere the force is to be applied is the opposite end of the head at thefurthest point away along the bending axis. By ‘resiliently flexible’ ismeant that when the 3 Newton force is removed, the head will return toits original position without the application of external force. Theangle through which the head bends when a 3 Newton force is applied asabove is referred to herein as the flex angle. The flex angle canconveniently be measured by measuring the vertical displacement (y) ofthe free end of the head under a 3 Newton force and the distance y andthe distance between the clamping point and the application of the force(x), the flex angle being derived by the relationship tan(flexangle)=y/x. In preferred embodiments the flex angle is at least 30, morepreferably at least 5° and it can be as high as 15° or more. Theconstruction of the head, in particular the dimensions of the groovesand hinges, the extent of elastomer filling of the grooves and hardnessof the elastomer is, however, such that the flex angle is limited toless than about 40°, preferably less than 30°, more preferably less than20°. This has been found to give an acceptable degree of flexibility forusers without exposing the hinges and elastomer-segment bonds to unduestress.

In highly preferred embodiments, only one of the opposed faces isbristle-bearing and when the head is in its normal unstressed state, thefree ends of bristles lying along a longitudinal axis of the brush forma generally concave profile. In highly preferred embodiments, thebristle-bearing face is concavely shaped. In these embodiments the headpreferably has a flex angle such that the bristle-bearing face of thehead is able to bend to the extent that the free ends of bristles lyingalong a longitudinal axis of the brush form a generally convex profile.The face of the head can be concave along either or both of theorthogonal axes of the head lying within the general plane of thebristle-bearing face. Where the face is concave along the longitudinalaxis, the radius of curvature may vary along the length of the head. Theradius of curvature is preferably from 10 to 500 mm, more preferablyfrom 15 to 250 mm, especially from 25 to 150 mm.

The brush head has bristles extending from one of the pair of opposingfaces. The bristles can be made of any of the materials well known inthe art. Suitable bristle materials herein are polyester and nylon, suchas Dupont Nylon 612. The bristles are preferably of circularcross-section but can also be of other cross-sections including, but notlimited to, rectangular, hexagonal and trilocular. Furthermore, thediameter and length of the bristles can vary within the usual dimensionsknown by a person skilled in the art. The bristles are generallyconventionally grouped into tufts and can be attached to the brush headby a variety of processes. Preferred processes herein are stapling andfusion. The bristles can be inserted into the segments or the elastomer,preferably into the harder material of the segments. Cutting andend-rounding of the bristles can be done using any of the methodscommonly known in the art.

Supply channels

A further essential feature of the toothbrush of this invention is oneor more elastomer supply channels extending between the elastomerichandle regions and the transverse grooves, whereby it least one,preferably all, of the elastomeric handle regions and the transversegrooves can be filled with elastomer from a single injection point. Inthe head these are conveniently provided by one or more longitudinalgrooves intersecting the transverse grooves.

In especially preferred embodiments the brush head comprises bothtransverse grooves on each of the opposed faces so that the head canbend along the longitudinal axis and at least one longitudinal groovewhich connects the transverse grooves and extending along the handle toconnect further with the voids that are used to form the handle grips.The longitudinal groove permits molten elastomer to flow from aninjection point to the elastomeric handle regions and then further tothe transverse grooves in the head.

This is generally achieved by a separate injection moulding step afterthe moulding of the handle and the segments of the head has beencompleted. Preferably, all of the elastomer is injected from a singleinjection point. A preferred method of making the toothbrush of theninvention comprises the step of injecting molten elastomer, preferablyat a temperature in the range from about 220° C. to about 260° C., morepreferably from about 230° C. to about 250° C., under pressure, into theinjection point and causing it to flow along the supply channel and intothe grooves. Suitable injection pressures are in the range from about 35MNm⁻² (350 bar) to about 50 MNm⁻² (500 bar), preferably from about 42MNm⁻² (420 bar) to about 48 MNm⁻² (480 bar).

In use, toothbrushes comprising the brush head of this invention can beused for cleaning the teeth by an entirely conventional tooth brushinghand action, preferably in a manner recommended by dental healthauthorities. The brush head of the invention can also be used inelectrically driven toothbrushes or children's toothbrushes.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example only, withreference to the accompanying drawings in which:

FIG. 1 is a partial side view of a first embodiment of the invention,depicting the toothbrush head with transverse grooves. Although the headis flat in its unstressed state, the bristles are cut to differentlengths so that the bristle surface is concave along the longitudinaldirection.

FIG. 2 is a plan view of a toothbrush head showing transverse grooves, alongitudinal groove acting as a supply channel, and discontinuoushinges. The bristles are omitted for the sake of clarity.

FIG. 3 is a perspective view of a toothbrush according to the invention.The bristles are omitted for the sake of clarity.

FIG. 4 is a perspective view of the toothbrush shown in FIG. 3 with theelastomer not shown in order to show the hinges, grooves and supplychannel more clearly.

FIG. 5 is a schematic showing the measurement of the flex angle.

Referring to FIG. 1, the brush head (1) has substantially parallel topand bottom faces, comprising segments (2) flexibly connected by hingesof head material (3). The top and bottom faces carry equal numbers ofgenerally parallel transverse grooves (4) filled with elastomer (5). Alongitudinal groove (not shown) connects the transverse grooves andextends into the handle (8), acting as a supply channel. Tufts ofbristles (6), extending from the top face, form a concave surface (7) attheir free ends.

Referring to FIG. 2, a toothbrush head (1) is formed integrally at oneend of a handle (8). The head includes three pairs of transverse grooves(4), one of each pair being on each of the top and bottom surfaces. Thetransverse grooves are in the form of waves and a single longitudinalgroove (9) connects the transverse grooves and extends into the handle,acting as a supply channel. The grooves are entirely filled withelastomer (5). The transverse grooves define segments of the head (2)which are connected to each other by hinges (3). There are gaps (10)between and to each side of the hinges so that in the gaps, theelastomer extends from top to bottom surfaces.

In FIGS. 3 and 4 the head (1) is co-moulded with the handle (8) and isconcave along its longitudinal aids on the bristle-bearing (upper)surface. Voids (11) in the handle are filled with elastomer to providehand grips (16). The voids are connected to each other by a longitudinalgroove (12) on the reverse side of the handle which extends into thehead and connects the transverse grooves (4) as shown in the view inFIG. 2. The elastomer in the voids and the grooves is injected from asingle injection point (13) and is of a different colour to the headmaterial to give a distinctive appearance. The head has holes (14)disposed on the top surface thereof to accommodate tufts of bristles.

FIG. 5 illustrates the measurement of the flex angle. The head (1) isclamped (15) against the first row of bristles (6) at the end which isattached to the handle (8) and a 3 Newton force (F) is applied to theopposite end. The dashed lines show the original position of the brushhead before the force is applied. The vertical displacement (y) of thefree end of the head under the force F is measured and the flex angle isderived from the distance y and the distance between the clamping pointand the application of the force (x) by die relationship tan(flexangle)=y/x.

What is claimed is:
 1. A toothbrush comprising: i) an elongated handle having distal and proximal ends and at least one elastomeric handle region therein; ii) a resiliently flexible head attached to the proximal end of the handle, the head including a pair of opposing faces, one of the pair being a bristle-bearing face with bristles attached to and extending from the face, wherein each of the opposing faces has a plurality of elastomer-containing transverse grooves extending completely through the head which divide the head into a plurality of segments; and iii) at least one supply channel extending between the elastomeric handle region and each of the transverse grooves so that the elastomeric handle region and the transverse grooves can be filled with elastomer from a single injection point.
 2. The toothbrush of claim 1, wherein there are at least three segments and each segment is interconnected to an adjacent segment by one or more hinges.
 3. The toothbrush of claim 2, wherein at least one of the one or more hinges is located nearest the handle and at least one of the one or more hinges is located most remote from the handle and wherein the hinge nearest the handle is up to three times as thick as the hinge most remote from the handle.
 4. The toothbrush of claim 2, wherein there is a gap between the plurality of hinges interconnecting each of the segments of the head.
 5. The toothbrush of claim 1, wherein the grooves are tapered.
 6. The toothbrush of claim 1, further comprising a plurality of hinges which interconnect each segment of the head with an adjacent segment.
 7. The toothbrush of claim 6, wherein at least two hinges interconnect each of the segments of the head with an adjacent segment and wherein there is a gap between each of the two hinges interconnecting each of the segments of the head.
 8. The toothbrush of claim 6, wherein each hinge is located between the opposing faces and at a distance of at least about 10% of the depth of the head from each of the faces, the hinges being less than the full width of the head.
 9. The toothbrush claim 6, wherein the grooves are non-linear.
 10. The toothbrush of claim 1, wherein the width of the grooves is between about 0.3 mm and about 3 mm.
 11. The toothbrush of claim 1, wherein one or more grooves are non-linear.
 12. The toothbrush of claim 11, wherein a portion of one of the non-linear grooves is directed toward the distal end of the handle.
 13. The toothbrush of claim 1, wherein the width of the grooves is between about 1.2 mm and about 2 mm.
 14. The toothbrush of claim 1, wherein the elastomer and the resiliently flexible head are formed from polymers based upon the same chemical class.
 15. The toothbrush of claim 1, wherein the transverse grooves in the opposing faces are partially offset from each other.
 16. The toothbrush of claim 1, wherein the transverse grooves in the opposing faces are completely offset from each other.
 17. The toothbrush of claim 1, wherein the transverse grooves in the opposing faces are directly opposed to each other.
 18. A toothbrush, comprising: i) an elongated handle having distal and proximal ends and one or more elastomeric handle regions therein; ii) a resiliently flexible head attached to the proximal end of the handle, the head including a pair of opposing faces, one of the pair being a bristle-bearing face with bristles attached to and extending from the face, wherein at least one of the pair has one or more elastomer-containing transverse grooves therein; iii) one or more elastomer supply channels extending between the one or more elastomeric handle regions and the one or more transverse grooves so that at least one of the elastomeric handle regions and the transverse grooves can be filled with elastomer from a single injection point; and wherein the one or more transverse grooves divide the head into a plurality of segments each of which are flexibly interconnected by at least one hinge to an adjacent segment, wherein each hinge is located between the opposing faces and at a distance of at least about 10% of the depth of the head from each of the faces, the hinges being less than the full width of the head and wherein the handle is made from an opaque material and the supply channel passes from one face of the handle to its opposite face so that, when filled with elastomer, the supply channel appears to be discontinuous.
 19. A toothbrush, comprising: i) an elongated handle having distal and proximal ends and one or more elastomeric handle regions therein; ii) a resiliently flexible head attached to the proximal end of the handle, the head including a pair of opposing faces, one of the pair being a bristle-bearing face with bristles attached to and extending from the face, wherein at least one of the pair has one or more elastomer-containing transverse grooves therein; and iii) one or more elastomer supply channels extending between the one or more elastomeric handle regions and the one or more transverse grooves so that at least one of the elastomeric handle regions and the transverse grooves can be filled with elastomer from a single injection point; and wherein the one or more transverse grooves divide the head into a plurality of segments each of which are flexibly interconnected by at least one hinge to an adjacent segment, wherein each hinge is located between the opposing faces and at a distance of at least about 10% of the depth of the head from each of the faces, the hinges being less than the fall width of the head and wherein grooves are tapered.
 20. The toothbrush of claim 19, wherein the one or more grooves are non-linear.
 21. A toothbrush, comprising: i) an elongated handle having distal and proximal ends and one or more elastomeric handle regions therein; ii) a resiliently flexible head attached to the proximal end of the handle, the head including a pair of opposing faces, one of the pair being a bristle-bearing face with bristles attached to end extending from the face, wherein at least one of the pair has a plurality of elastomer-containing transverse grooves therein which divide the head into a plurality of segments; iii) at least one supply channel extending between the elastomeric handle region and each of the transverse grooves so at that the elastomeric handle region and the transverse grooves can be filled with elastomer from a single injection point; and wherein the grooves are tapered. 